[Pkg-sysvinit-devel] A wish for help with Bug#765803 On automatic init system switching on upgrade

[Svante Signell]

Hello pkg-sysvinit-devel
Cc: seconds of the init system coupling GR

Reading the latest replies on #765803 reveals that the ctte issue in
that bug will probably not be resolved, and status quo will force all
upgrades to systemd-sysv (in addition to new installations). It seems
that the people opposing an automatic upgrade has to propose technical
solutions to avoid this to happen, before the (now reduced) TC can make
a decision. On way to solve this is to add a debconf prompt
(unfortunately frowned upon) when upgrading from wheezy/testing as
follows:

(for new installs the situation is different, with the installer
choosing systemd-sysv by default, and you can only install sysvinit-core
after the first reboot)

Package: init
Source: init-system-helpers
Add a build dependency on debconf
Script file: init-system-helpers.postinst + template file(s)
One problem is that that package is maintained by the Debian Systemd
Maintainers, so I cannot ask for help from them.

1) Detect if sysvinit-core is installed: If not:

Issue a warning: You are about to switch init system, do you want that?
yes) continue
no) Install sysvinit-core (and if needed systemd-shim): Is that
possible? 

Otherwise abort the upgrade and give a link to documentation (release
notes??) about how to avoid switching init, including the pinning trick:
create /etc/apt/preferences.d/no-systemd-sysv:
Package: systemd-sysv
Pin: release o=Debian
Pin-Priority: -1

2) Detect if systemd-shim is installed: If not:

(How to detect a desktop installation?)
Issue a warning: You are about to install systemd components including
systemd-sysv, i.e. changing init, do you want to do that?
yes) continue
no) install systemd-shim

If the user wants a systemd-free desktop/server:
creating /etc/apt/preferences.d/no-systemd:
Package: systemd
Pin: release o=Debian
Pin-Priority: -1
(is this really sufficient to avoid any systemd package??, as
systemd-must-die did)

I've looked at the debconf tutorial,
http://www.fifi.org/doc/debconf-doc/tutorial.html, but I'm not fluent in
doing this and would appreciate help (If there is interest, otherwise we
just give up??)

Please forward this mail to anybody who might want to help. Time is
short, 4th of December is the deadline.

Thanks in advance!